feat: finish summary and application for clap.

- finish summary and application for clap.
- add patch for utf8 string in std::format.

src/yycc/string/format.hpp

@@ -0,0 +1,78 @@
+/**
+ * @file
+ * @brief The patch for \c std::format to allow UTF8 string as arguments.
+ * @details
+ * As we known, \c std::format only allow \c char and \c wchar_t as its char type in C++ 23 currently.
+ * So it is impossible to use UTF8 string for std::format, both format string and argument.
+ * This namespace give a patch for this shortcoming.
+ * By including this file directly, you will have abilities that use UTF8 string as argument in \c std::format with \c char char type.
+*/
+#pragma once
+#include "reinterpret.hpp"
+#include <format>
+#include <string>
+#include <string_view>
+
+#define NS_YYCC_STRING_REINTERPRET ::yycc::string::reinterpret
+
+#pragma region Utf8 Formatter
+
+// Add std::formatter specialization for "char8_t*"
+template<>
+struct std::formatter<char8_t*, char> {
+    constexpr auto parse(auto& ctx) { return underlying_formatter.parse(ctx); }
+    auto format(char8_t* str, auto& ctx) const { return underlying_formatter.format(NS_YYCC_STRING_REINTERPRET::as_ordinary(str), ctx); }
+
+private:
+    std::formatter<const char*, char> underlying_formatter{};
+};
+
+// Add std::formatter specialization for "const char8_t*"
+template<>
+struct std::formatter<const char8_t*, char> {
+    constexpr auto parse(auto& ctx) { return underlying_formatter.parse(ctx); }
+    auto format(const char8_t* str, auto& ctx) const {
+        return underlying_formatter.format(NS_YYCC_STRING_REINTERPRET::as_ordinary(str), ctx);
+    }
+
+private:
+    std::formatter<const char*, char> underlying_formatter{};
+};
+
+// Add std::formatter specialization for "char8_t[N]"
+template<std::size_t N>
+struct std::formatter<char8_t[N], char> {
+    constexpr auto parse(auto& ctx) { return underlying_formatter.parse(ctx); }
+    auto format(const char8_t (&str)[N], auto& ctx) const { return underlying_formatter.format(std::basic_string_view<char>(str, N), ctx); }
+
+private:
+    std::formatter<std::basic_string_view<char>, char> underlying_formatter{};
+};
+
+// Add std::formatter specialization for "std::u8string"
+template<class Traits, class Alloc>
+struct std::formatter<std::basic_string<char8_t, Traits, Alloc>, char> {
+    constexpr auto parse(auto& ctx) { return underlying_formatter.parse(ctx); }
+    auto format(const std::u8string& str, auto& ctx) const {
+        return underlying_formatter.format(NS_YYCC_STRING_REINTERPRET::as_ordinary_view(str), ctx);
+    }
+
+private:
+    std::formatter<std::basic_string_view<char>, char> underlying_formatter{};
+};
+
+// Add std::formatter specialization for "std::u8string_view"
+template<class Traits>
+struct std::formatter<std::basic_string_view<char8_t, Traits>, char> {
+    constexpr auto parse(auto& ctx) { return underlying_formatter.parse(ctx); }
+    auto format(std::u8string_view sv, auto& ctx) const {
+        return underlying_formatter.format(NS_YYCC_STRING_REINTERPRET::as_ordinary_view(sv), ctx);
+    }
+
+private:
+    std::formatter<std::basic_string_view<char>, char> underlying_formatter{};
+};
+
+#pragma endregion
+
+#undef NS_YYCC_STRING_REINTERPRET